Background:
The intensive mollusc farming is an activity carried out in floating farms named “bateas” (rafts in English). These structures have been traditionally made with eucalyptus wood, as it is economic and provides the flexibility necessary to adapt to the swell. However, their durability is very limited, lasting between 8 and 20 years. Thus, RDC patented in 2015 a design of raft made with UHPC, having similar stiffness and weight but much higher durability. With the support of the European Commission (project SELMUS-738777, SME Instrument Phase 2) RDC installed four full-scale prototypes that helped to show to the farmers the minimum maintenance requirements of these resilient structures.
Currently, these elements are produced by the company PREFFOR (owned by RDC founders) under the name of Formex® rafts. In 2022 there are already more than 20.000 m2 of Formex® rafts in the Atlantic, Mediterranean, Baltic and North Sea basins, having different sizes and functionalities depending on the marine conditions and requirements of the farmers.
Why to use UHPC?
UHPC performance is key in this application for several reasons. Its very high compressive strength allows to design a very prestressed beam, so that it can be very flexible under service and avoiding microcracking to guarantee durability. Besides, the absence of secondary reinforcement and the reduced cover implies that the beams can be as light as the eucalyptus logs, so the UHPC raft can be installed with the same steel floaters are the traditional solutions. Finally, the durability of the UHPC implies that the structure has a lifespan higher than 50 years and the yearly painting required in the traditional rafts is avoided, saving costs, risks and reducing the carbon footprint.
Advantages:
- Maintenance significantly reduced compared to traditional structures
- High resiliency. Fire and impact strength.
- Bolted connections allow a simple decommissioning and reuse of the standardized elements.
Achievements:
- First world application with UHPC in the aquaculture sector.
- Solution patented in Spain (2015)
- Currently there are submersible Formex® rafts and connectable Formex® rafts in the spectrum of products
